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Studies the radial stem growth in Salix cinerea on Lake Vyrnwy margin in Wales. Disposition of Salix cinerea groupings; Vertical distribution of the Salix cinerea trees on the margin; Mean ages of the Salix cinerea groupings at Lake Vyrnwy.

Using willow stem segments it has been possible to show that the presence of gibberellic acid in the xylem can influence the lateral mobility of radioactive indolylacetic acid and its principal metabolite, indoleacetylaspartic acid. The extent of the lateral movement of indolylacetic acid depends on the concentration of endogenous gibberellin in the xylem, and movement may be increased by exogenous gibberellin applications to the xylem. The mechanism controlling the lateral movement of 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid appeared to be somewhat different and there was no positive movement towards gibberellin. These results arc discussed in relation to previous experimentation on the interaction of plant growth regulators during transport. It is suggested that gibberellins may influence cell membranes and this may account for their effects on the transport of indolylacetic acid. [ABSTRACT FROM AUTHOR]

Rooting on 2.5 cm long stern segments of Salix tetrasperma was optimal when cultured in 5.0 mg/I IAA in combination with 1.0 % glucose at 30°C, and in combination with 0.1 % glucose at 15°C. 5-Fiuorodeoxyuridine (FUDR), actinomycin-D and cycloheximide all inhibited rooting and the inhibitory effect in each case increased with concentration. 5-Fluorouracil (FU), on the other hand, was ineffective. The results show that auxins probably act as a triggering agent for the synthesis of specific enzyme proteins that are required for the initiation of root primordia at the transcriptional level and that a correct balance of auxin and nutrition which may vary with the environmental conditions, is necessary for optimal rooting. [ABSTRACT FROM AUTHOR]

Labelled maleic hydrazide (MH) was shown to be accumulated preferentially into the root-tips of young Willow roots by radiochemical analysis. A large proportion of the activity incorporated into the cell constituents was associated with RNA. MH was also bound in some way to the cell wall material. The greatest proportion of the activity was easily removed from the root tissue and thus probably occurred free within the cytoplasm and free-space. The incorporation of MH into RNA and its subsequent effects on cell metabolism via abnormal protein and enzyme synthesis is given as an explanation of the mode of action of MH. [ABSTRACT FROM AUTHOR]

Role of water in centrifugal root promotion, effect of centrifugation on thylene concentration of cuttings, and effect of ethylene on root formation were investigated using Salix fragilis softwood cuttings. When cuttings were centrifuged with water, more roots formed with increasing water depth. Smoking of cuttings up-right in water for 24 h stimulated root formation and produced more roots as the depth of water was increased, with submerged cuttings producing the highest number of roots Soaking of cuttings upright in hot water for 1 h also stimulated root formation with the best root formation occurring at 40 °C. Submerging in, or centrifuging with water increased ethylene concentration in cuttings. Ethylene gas and Ethrel treatments stimulated root formation. It is suggested that sub-merging in water increases the thylene concentration in Salix fragilis softwood cuttings which in turn stimulates root formation of the cuttings. Centrifuging cuttings with water increased water content of the cutting. It is suggested that this increase in water content plays role similar to the submersion of cutting as described above. [ABSTRACT FROM AUTHOR]

Willow cuttings were used in which a narrow, longitudinal strip of bark was removed commencing from the base of the leafy shoot. Aphid colonies of different sizes were then sited on the stem either side of the strip, 10 cm below the base of the shoot. The leaves were allowed to assimilate 14CO2, and the dry weight and total activity of the honeydew from each colony was measured over a given period of lime. It was found that not only did the total activity from the large colony exceed that of the small colony, but that the specific activity of the honeydew from tile large colony was higher than that from the small colony. This has been taken as evidence that neighbouring pierced sieve tubes do not act independently of each other; mutual interference occurs. Increasing the distance between pierced sieve elements by dispersing the members of the large colony over a greater area of stem, did not apparently reduce interference effects. The results are explained in relation to the magnitude of the contributory length (Peel and Weatherley 1962), of individual sieve tubes pierced by the large, as opposed to the small colony. [ABSTRACT FROM AUTHOR]

This article presents a study report of the salt tolerance of various poplar and willow species and clones conducted in the laboratory and field. The resistance of 10 black and 10 grey poplar clones and of 36 willow-clones was examined by dipping shoots in a highly concentrated NaCl solution. All the black and most of the grey poplars showed high resistance. Only eleven willow-clones showed sufficient resistance. The studies are to be continued with enlarged material under various ecological conditions.

The use of a slide agglutination test on squeezed-out sap of cultivated cricket bat willow trees allowed rapid diagnosis of infection by Erwinia salicis in the field. By this means, infection of ‘classically’ diseased willow trees with both red leaf and wood staining was confirmed. Trees with either red leaf or wood stain, but not both symptoms, were also shown to be infected. Symptomless infection of cricket bat willow trees was detected. E. salicis was viable in the stumps of trees felled five years previously. Some of these stumps were in an advanced state of decay and some were producing symptomless leafy shoots. Trees dying with severe die-back symptoms and infected with Armillaria mellea, were shown to be infected with E. salicis. Salix caprea and S. vitellina, two wild species of willow, were also shown to be infected. [ABSTRACT FROM AUTHOR]